Possible Duplicate:
Which is correct: “soda” or “pop”?
Is it correct to say soda, or is it pop, or is it soda pop?
My friend and I are going back and forth: he says soda is "Soda ash" (Sodium carbonate) and pop doesn't sound right (ie, "a loud POP", or the "pop" music).
Merriam-Webster Online Dictionary gives
SODA (definition 2)
a : soda water 2a
b : soda pop
c : a sweet drink consisting of soda water, flavoring, and often ice cream
SODA POP
a beverage consisting of soda water, flavoring, and a sweet syrup
POP, noun (definition 2)
soda pop
So which one is right? Which would be the correct grammar usage, would I use both, neither or what?